1. Technical Field
The present invention generally relates to apparatus for welding wax components. More particularly, the present invention relates to heating an area of a surface of a wax runner to form a confined wax pool thereon in preparation for fusing a wax pattern to the wax runner to prevent excess molten wax from running over the side of the wax runner.
2. Background Information
The Lost Wax Process is a long-established process for casting metal parts. In the practice of the Lost Wax Process, a wax pattern of a part to be cast is molded in wax. When the wax pattern is molded, a pattern gate is molded with the wax pattern in one piece. Wax runners are also molded separately. Wax runners are usually at least one branch, frequently with flat surfaces and two ends. Some wax runners have a circular cross section and thus do not have either flat surfaces or edges. At one end of the runners there is a head and the other end there is a tail. A pour cup may be located at the head. The wax patterns are affixed by their gates to the wax runners to form a wax tree. In order to fuse the gate of a wax pattern to a wax runner, both the surface of the wax pattern's gate and the surface of the wax runner are heated sufficiently to melt wax to permit fusion. Once the wax patterns are affixed to the wax runner, a wax tree has been formed. Then ceramic material is placed on the wax tree. After the ceramic has hardened, the ceramic-coated wax tree is heated, causing the wax to melt and flow out of the ceramic. Removal of the wax yields a ceramic mold into which molten metal is poured to produce the desired part.
In recent times, much of the Lost Wax Art has been substantially automated. In U.S. Pat. No. 6,910,519 issued to Ludwig, et al., entitled “Process and Apparatus for Assembly of Wax Trees,” assigned to the same assignee, an advanced process and apparatus is taught for automating the fusion of wax gates of wax patterns to a wax runner. As taught in this patent, a heated blade is used to heat the wax pattern gates and the wax runner before they are fused together.
Since it may be difficult to hold a surface of a wax runner in a flat, horizontal position when attaching the wax patterns, portions of the wax runner may be penetrated more deeply by the heated blade than other portions. When this occurs, excess molten wax may be produced on some areas of the wax runner, and if the excess melted wax runs over the side of the wax runner, the wax runner and the wax patterns attached to it are not useable. This results in lost product. A similar problem may occur due to variations in the surface of a wax runner or warping of the wax runner.
Therefore, a need exists for wax pattern welding apparatus and a method of heating wax on the surface of a wax component that produce a pool of molten wax which is confined to an area of the surface of the wax runner to prevent excess molten wax from running over the side of the wax runner.